How ancient humans killed off Africa’s rainforests

Three thousand years ago, Africa was covered in evergreen forests that were slowly transforming into savannah and grassland as the climate warmed. But even 3,000 years ago, natural variation in climate was apparently not enough to wreak serious habitat havoc. For that you need humans. And as it turns out, humans radically accelerated the loss of Africa’s forests, reports Rachel Nuwer at ScienceNOW.

The paper’s results, published online today in Science, came as a surprise to the researchers. “To be honest, at the beginning we were not at all aware of this human issue,” says lead author Germain Bayon.

Back then, instead of humans causing climate change, climate change caused humans. Or anyway, the warming climate made for conditions that were more hospitable to agriculture, contributing to the rise of human civilization — and the fall of the forests. Bantu farmers cut down trees so they could grow pearl millet and yams, which contributed to soil loss and erosion.